Influenza vaccine prevents influenza illness, hospitalization, and death. Hospitalized children are at increased risk of influenza-related complications due to medical comorbidities. However, hospitalized children have lower influenza vaccine coverage than the general population. Many hospitalized children do not have good access to outpatient medical care where they could receive vaccine. Therefore, hospital visits are a critically important encounter to provide influenza vaccine to eligible patients. Clinical decision support (CDS) interventions have the potential to improve influenza vaccine uptake and other health maintenance interventions in hospitalized children. Our long-term objective is to identify CDS strategies that improve uptake of recommended health maintenance interventions in acute care settings. In this proposal, we aim to develop and evaluate CDS to promote influenza vaccine in hospitalized children that can be shared via CDS Connect for use across institutions. We will also identify insights that apply to CDS for health maintenance interventions in acute care settings more generally. In Aim 1 of this proposal, we will use user-centered design best practices to develop CDS to promote influenza vaccine uptake for inpatients at three children?s hospitals within a single health system. We will first perform a user and task analysis with relevant stakeholders to understand goals and barriers related to the influenza vaccine administration process as well as provision of health maintenance interventions more generally. We will then design candidate CDS strategies based on these insights and iteratively improve upon them with stakeholders through scenario-based formative usability testing. Finally, we will evaluate CDS effectiveness in simulations through summative usability testing. We will publish the final CDS strategy on CDS Connect. In Aim 2, we will implement the CDS sequentially across care settings within the three hospitals and evaluate implementation effectiveness using the RE-AIM framework. We will use electronic health record queries, surveys of operational leaders and CDS developers, and observations of admitting clinicians to determine the reach of the intervention, its efficacy to improve influenza vaccine administration, adoption by individual clinicians and organizational leaders, implementation fidelity, and costs of maintenance. At the end of this project, we will have developed and evaluated a CDS process to promote influenza vaccine in pediatric acute care settings at a single center. We will also have published the CDS strategy on CDS Connect and associated it with key quantitative and qualitative data required by health systems to facilitate implementation such as the expected impact, expected costs of implementation, and local customization points for adaptation. These results will lay the groundwork for multicenter studies of CDS to improve influenza vaccine uptake and related health maintenance interventions for hospitalized children.